3D Printer File Creation for Art

I am looking for an experienced individual to create an STL file for a 3D printer. The file will be used specifically for creating a piece of art or decoration. This piece will need to be of medium detail, focusing on general shapes and some texture. Not that it’s important to know but this is a piece printed that will be attached to an electric guitar. It’s more for cosmetic purposes than anything. Approximately 3.5 x 3.5 inches in size if that info is needed in advance. I have access to a friend’s printer & I’m told a .STL file is what’s needed.